In medical treatment therapy, individuals may require the intravenous administration of various types of fluids containing amino acids, dextrose, lipid emulsions and/or various types of vitamins and drugs. Types of storage containers and methods of administering such fluids to patients have been developed and are known in the art.
One known type of storage container is constructed of flexible, medical grade polyvinyl chloride (PVC). The container can be constructed of two sheets of PVC material, for example, and bonded together along the periphery to form a container bag. Access to the bag is provided, for example, by a port tube communicating with the interior of the container and sealed between the two sheets of the container. A membrane tube having an inner pierceable membrane can be secured by solvent bonding, for example, to the interior of the end of the port tube opposite the end that communicates with the interior of the container. Access to the container can be achieved by inserting a spike through the inner pierceable membrane of the membrane tube. The spike is attached to tubing which can be directed into a patient, for example.
Polyvinyl chloride material is currently the best type of material to be used for the membrane tube, including the inner pierceable membrane. Use of PVC material for the membrane allows relatively easy insertion and withdrawal of the spike from the membrane and provides a good seal between the membrane and the spike.
For storing materials such as amino acids, dextrose solutions, lipid emulsions, fat soluble vitamins, and various types of drugs and medications, such as nitroglycerin, an improved container material has been developed. The improved container material is ethylene-vinyl acetate (EVA) and exhibits several advantages over flexible PVC material. Containers made from ethylene-vinyl acetate material exhibit less leaching of material into the fluid being stored in the container. Another advantage is that certain materials which may be stored in the container will be absorbed to a lesser degree by ethylene-vinyl acetate material than PVC material. Thus, for some applications, storage bags made of ethylene-vinyl acetate material are preferred to PVC bags.
In order to maximize the usefulness of EVA containers, a port tube and port and membrane tube assembly specifically for use with EVA containers is needed. Various types of port tubes and membrane tubes have been utilized with EVA containers but none has been completely acceptable. For example, an EVA port tube has been utilized with an EVA membrane tube. Use of an EVA port tube with an EVA container results in a good bond which can be formed by using radio frequency (R.F.) energy. However, it is not practical to R.F. bond the EVA membrane tube to the EVA port tube since the membrane could be damaged by R.F. energy thereby possibly affecting the sterility of the container. The EVA membrane tube can be cemented into the EVA port tube with a cement comprising about 90% toluene and 10% of EVA. However, this has disadvantages since the adhesive must be heated and agitated for several hours to produce a homogeneous cement. Further, the cement requires a minimum drying time of twenty-four hours before further processing or testing.
Use of an EVA membrane tube is not completely acceptable for other reasons. Insertion of a spike through the EVA membrane is relatively difficult. Further, removal of the spike generally does not occur without separating the membrane tube from the port tube due to the relatively weak bond strength provided by cementing the EVA membrane tube into the EVA port tube and the adherence of the EVA membrane to the spike. When removal of the spike causes separation of the membrane tube from the port tube, the spike and its associated tubing and connections must be discarded since a suitable method of aseptically removing the EVA membrane tube from the spike is not available. Since one patient may require as many as four bag or container changes in a twenty-four hour period, this results in the use of a large number of spikes and associated tubing and connections.
The use of a PVC port tube with a PVC membrane tube or an EVA port tube with a PVC membrane tube is not feasible with an EVA container since a suitable method of bonding the PVC to EVA is not available. For example, a suitable bond between EVA and PVC is not obtained with R.F. energy due to the incompatibilities of PVC and EVA.
Thus, a need exists for a suitable port tube and port and membrane tube assembly for use in connection with a flexible EVA container and a ported EVA container that is suitable for medical uses that overcome the foregoing disadvantages, including difficulty in spike removal and separation of the membrane tube from the port tube.